earlier, a police officer had been shot dead there at the massachusetts institute of technology in cambridge. kurt shorts, the under secretary for homeland security and emergency management, gave an outline to the measures being taken in the watertown area. >> to the residents of watertown, newton, waltham, belmont, cambridge, and the allston brighton neighborhoods of boston, we are asking you to stay home, stay indoors. we are asking businesses not to open. we are asking people not to congregate outside. we are asking people not to go to mass transit. and we are hopeful that as the day proceeds that we can provide further guidance and will be able to open portions of the system and be able to ease these rest